Originally named "Okatana Yoshimitsu" (御刀吉光), Ichigo Hitofuri once belonged to the Asakura clan of Echizen province until the family was destroyed in 1573 during the course of Oda Nobunaga’s seizure of power, which transferred its ownership to the Mōri clan. On the 18th of September 1590, Toyotomi Hideyoshi visited the Mōri estate and the sword was given to him. Toyotomi Hideyoshi wanted to wear Ichigo Hitofuri by all means and ordered the blade to be shortened to match his rather short height.
Ichigo Hitofuri was damaged in the summer of 1615 during the Siege of Osaka at Osaka Castle and then re-tempered by Yasutsugu under the order of Tokugawa Ieyasu. However, Ieyasu didn’t get the chance to use this sword because he was advised by the Priest Tenkai to avoid sending Hideyoshi’s swords (including Ichigo Hitofuri) to Edo. Ichigo Hitofuri remained in possession of the Owari branch of the Tokugawa until Tokugawa Mochinaga presented the sword to Emperor Koumei on January 29th, 1863 and it has been an Imperial treasure since that time, alongside Tsurumaru Kuninaga, Uguisumaru and Hirano Toushirou.
The game subscribes to the interpretation that Ichigo Hitofuri is the only tachi forged by Awataguchi Yoshimitsu; in actuality, it is known that another tachi was associated with Yoshimitsu - Kaikiri Yoshimitsu (owned by the Kyougoku clan), which construes Ichigo Hitofuri as the namesake of Yoshimitsu's lifetime masterpiece.
Fans enjoy portraying him as the big brother of the Toushirou tantous, due to him being the biggest/tallest blade among Yoshimitsu's creations, not because he's the oldest among them.
Some fans theorized that his hair color is based on the color of Osaka Castle's roofs.
Ichigo Hitofuri and Mikazuki Munechika can be considered Spousal Swords (夫婦刀) for their once owners being Toyotomi Hideyoshi and his wife Nene/Kodai'in respectively.
He mentioned his clothes being too flashy (imperial-ish), this actually refers to his status as an Imperial treasure.